Charge Variant Analysis Service

Monoclonal antibodies (mAbs) are complex proteins susceptible to numerous post-translational modifications (PTMs) that may induce charge heterogeneity. Antibody charge variants can have a potential influence on product stability and biological activity, making it necessary to monitor these charge variants during the development of therapeutic mAbs. Having focused on therapeutic antibody development and characterization for more than a decade, Creative Biolabs offers comprehensive PTM analytical services to analyze antibody charge variants during different stages of your antibody development and manufacturing processes.

Introduction to Antibody Charge Variants

mAbs undergo chemical degradation via several different mechanisms, including oxidation, deamidation, isomerization, and fragmentation, that result in the formation of various charge variants and heterogeneity, thus modifying their isoelectric pH (pI) values. These variants are generally referred to as acidic or basic species as compared with the main species. Common sources of charge-related heterogeneity of therapeutic IgG1 mAbs include but are not limited to:

• Deamidation and sialylation that brings an increase in the net negative charge and cause a decrease in pI values, thereby leading to the formation of acidic variants;
• C-terminal lysine cleavage that results in the loss of net positive charge, thereby leading to acidic variant formation;
• The formation of various types of covalent adducts, e.g., glycation;
• N-terminal cyclization that results in positive charge loss of antibodies due to the conversion of the N-terminal amine to a neutral amide;
• Formation of the basic variants can result from the presence of C-terminal lysine, or glycine amidation, succinimide formation, amino acid oxidation, or removal of sialic acid, which introduce additional positive charges or remove negative charges.

Fig.1 IgG charge micro-variants and their importance. (Wagner-Rousset, 2017)

The Necessity for Antibody Charge Variant Analysis

mAb charge heterogeneity has been reported to potentially impact on efficacy, potency, immunogenicity, and clearance. Evidence has presented that deliberately modifying the pI of an antibody by approximately one pI unity or more can give noticeable differences in the pharmacokinetics (PK) of an intact mAb. Moreover, the characterization and monitoring of these charge variants are critical quality requirements to ensure stability and process consistency.

mAb Charge Variant Analysis Services

Creative Biolabs now offers comprehensive mAb charge variant analysis services to isolate and identify different charged variant forms using different charged-based separation techniques (e.g., capillary isoelectric focusing (cIEF)), chromatography techniques, or mass spectrometry (MS)-based analytical methods. Moreover, we can offer a wide range of antibody function assays to help understand the effects of these variants on antibody activity and properties, such as effector functions, FcRn, and antigen binding affinity, and PK, thereby elucidating the structure-function relationships.

If you are interested in our services, please do not hesitate to contact us for more details.

Reference

1. Wagner-Rousset, E.; et al. Development of a fast workflow to screen the charge variants of therapeutic antibodies. Journal of Chromatography A. 2017, 1498: 147-154.

For Research Use Only.